Abstract: In vitro laboratory studies were conducted to test the efficacy of hydrogen peroxide (OxiDate™) in inhibiting the growth of the pink rot of potato fungus, Phytophthora erythroseptica. In addition to the control, three concentrations (1:250, 1:100 and 1:50 of hydrogen peroxide to water) were tested. A total of 40 different P. erythroseptica isolates originated from New Brunswick and Prince Edward Island (Canada) and from Maine, Idaho, Minnesota, Oregon and Wisconsin (USA) were subjected to the various concentrations of hydrogen peroxide in a replicated experiment using a Completely Randomized Design. Growth of all isolates was completely inhibited when the 1:50 concentration was used. At the 1:100 concentration, growth of 94.2% of the isolates tested was completely inhibited. At the lowest concentration of 1:250, the growth of 41.4% of the isolates tested was completely inhibited. The results of this study suggest that hydrogen peroxide has the potential to be used for post harvest treatment of potatoes against P. erythroseptica that might be present on the surface of the tubers.